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Roof bolt bit

Roof bolt bit description/claims

This application is a continuation-in-part of U.S. patent application Ser. No. 11/774,667 which is a continuation-in-part of U.S. patent application Ser. No. 11/766,975 and was filed on Jun. 22, 2007. This application is also a continuation in-part of U.S. patent application Ser. No. 11/774,227 which was filed on Jul. 6, 2007. U.S. patent application Ser. No. 11/774,227 is a continuation-in-part of U.S. patent application Ser. No. 11/773,271 which was filed on Jul. 3, 2007. U.S. patent application Ser. No. 11/773,271 is a continuation in-part of U.S. patent application Ser. No. 11/766,903 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,903 is a continuation of U.S. patent application Ser. No. 11/766,865 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,865 is a continuation in-part of U.S. patent application Ser. No. 11/742,304 which was filed on Apr. 30, 2007. U.S. patent application Ser. No. 11/742,304 is a continuation of U.S. patent application Ser. No. 11/742,261 which was filed on Apr. 30, 2007. U.S. patent application Ser. No. 11/742,261 is a continuation in-part of U.S. patent application Ser. No. 11/464,008 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/464,008 is a continuation-in-part of U.S. patent application Ser. No. 11/463,998 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,998 is a continuation in-part of U.S. patent application Ser. No. 11/463,990 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,990 is a continuation in-part of U.S. patent application Ser. No. 11/463,975 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,975 is a continuation in-part of U.S. patent application Ser. No. 11/463,962 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,962 is a continuation-in-part of U.S. patent application Ser. No. 11/463,953, which was also filed on Aug. 11, 2006. The present application is also a continuation in-part of U.S. patent application Ser. No. 11/695,672 which was filed on Apr. 3, 2007. U.S. patent application Ser. No. 11/695,672 is a continuation-in-part of U.S. patent application Ser. No. 11/686,831 filed on Mar. 15, 2007. All of these applications are herein incorporated by reference for all that they contain.

This invention relates to drill bits, more specifically to improvements in drill bits used for drilling in mine roof bolting operations.

Such drill bits are subjected to large torsional and axial forces, high rotational speed, heat, and abrasion. These environmental factors may cause wear on the cutting elements and the bit body. Long bit life is desirable to reduce the machine downtime required to replace the bit and the associated cost. Extending time between bit replacements may reduce the time spent by mine workers in dangerous, unsupported areas. Roof bolt bits have been disclosed in the prior art.

U.S. Pat. No. 5,535,839 to Brady, which is herein incorporated by reference for all that it contains, discloses a rotary drill bit having a head portion with at least two hard surfaced inserts having domed working surfaces and being oppositely oriented to face in the direction of rotation at positive rake angles, and a mounting adapter for removably securing the drill bit to a drilling machine.

U.S. Pat. No. 5,429,199 to Sheirer, which is herein incorporated by reference for all that it contains, discloses a cutting bit useful for cutting various earth strata and the cutting insert, which may be made from a polycrystalline diamond composite, for such a cutting bit. The cutting bit has at least one pocket at the axially forward end thereof which receives its corresponding cutting insert. The cutting insert has at least one exposed cutting edge which is of an arcuate shape.

U.S. Pat. No. 4,550,791 to Isakov, which is herein incorporated by reference for all that it contains, discloses a two-prong rotary drill bit, especially for use with roof drills. The two-prong bit has a supporting body having an axis of rotation. The two-prong bit has a pair of inserts, one insert on each of the prongs. Each of the inserts has a cutting portion facing in the direction of rotation and a mounting portion. When viewed in a direction parallel to the axis of rotation, each of the inserts will have a cross-sectional configuration which is generally wedge-shaped. Also disclosed are wedge-shaped inserts especially for use with roof drill bits.

In one aspect of the present invention, a mining roof bolt bit comprises a bit body intermediate a shank and a working surface, the shank being adapted for attachment to a driving mechanism. The working surface comprises a plurality of polycrystalline diamond enhanced cutting elements. Carbide bolsters are disposed intermediate the cutting elements and the bit body.

The plurality of polycrystalline diamond cutting elements may comprise pointed geometry. The pointed geometry may comprise a thickness of 100 inch or more, and may comprise a radius, preferably between 0.050 inch and 0.200 inch. At least one of the plurality of polycrystalline diamond cutting elements may comprise a central axis intersecting an apex of the pointed geometry, and the central axis may be oriented within a 15 degree rake angle. The working surface may comprise an indenting member disposed substantially coaxial with the rotational axis of the bit. The indenting member may comprise a polycrystalline diamond element disposed on the distal portion of the indenting member. The indenting may depend axially from the bit body less than, equal to, or greater than the cutting elements.

The carbide bolsters may be brazed to the bit body, preferably at a non-planer interface. The carbide bolsters may comprise a substantially conical portion, and may comprise a flat. The flats may be brazed together, and the bolsters may also comprise geometry adapted to interlock with one or more other carbide bolsters. The bolsters may comprise a cavity, and an end of a shaft may be interlocked in the cavity. An opposite end of the shaft may be adapted to be attached to the bit body by threads or other methods.

The carbide bolsters may comprise a substantially straight cylindrical portion at least mostly disposed below the surface of the bit body, a top end and a bottom end, the top end narrowing from the cylindrical portion with a substantially annular concave curve to a planer interface adapted for bonding to a carbide substrate, and the bottom end narrowing from the cylindrical portion to a stem.

In some embodiments, the bit may be adapted for use with a driving mechanism comprising a hammer mechanism adapted to oscillate the bit axially.

The bit may comprise vacuum ports in communication with a vacuum source in the driving mechanism to provide vacuum to the working surface of the bit. In some embodiments of the present invention, the bolsters are press fit into the bit body. In some embodiments, the cutting elements comprise a substantially conical geometry with a rounded apex and a wall of the conical geometry forming an included angle with a central axis of the cutting element of 70 to 90 degrees. The carbide substrates may be less than 10 mm in axial thickness.

FIG. 1 is an orthogonal view of an embodiment of a roof bolting machine.

FIG. 2 is a perspective view of an embodiment of a roof bolt bit.

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• Utility Patent

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